Option B has the grammatically incorrect part. The error is in the use of the wrong preposition 'with' in the given sentence.

• The verb accustomed agrees with the preposition 'to' and not 'with'. 
  e.g. He was accustomed to hearing and safeguarding the secrets of others.
  
• Thus, replace 'with' with 'to' to make the sentence grammatically sound. 

Option B has the grammatically incorrect part.

• The first part of the sentence "A dozen Geography books lying on the shelf of my personal library" does not form a complete sentence. 
  
• For the verb "lying", we need an auxiliary before it. 
  
• It should be in the present tense.
  
• For the plural subject "A dozen Geography books", use the plural auxiliary "are".

Option A has the grammatically incorrect part.

• The verb "ration" means to limit the amount of a particular thing that someone is allowed to have.
  
  
• Here, after the auxiliary "was", we need a V3 form.
  
  e.g. Petrol was so strictly rationed that bikes were always in demand.
  
  
• Thus, "rationed" should be used here. 

The correct sentence will be: Do you remember when petrol was rationed to five gallons a week?

• The sentence states that some people are not expecting the dear once, though, they managed to cook an awesome meal.

• Word 'marvel' is a noun here that means something that causes feelings of wonder. But we don't need a noun here, in place of it we need an adjective for the noun 'meal'.

• Thus, 'marvelous' should be used in place of 'marvel' to make the sentence grammatically correct.

• 'Marvelous' means extraordinarily good or great; used especially as an intensifier.
  • E.g. :- A marvelous collection of rare books.

Option C has the grammatically incorrect part. 

• An adverb is used to qualify a verb. So, be cautious to use the correct adverb.
  
• Here, in the given sentence, “asked” is the verb and we are using “repeated” (an adjective) to qualify a verb. This is wrong. 
  
• Thus, the appropriate adverb should be used here i.e. “repeatedly”.
  
• Repeatedly means “many times”;
  For example: He had been stabbed repeatedly in the abdomen.

Thus, the correct sentence will be: Sneha's father has repeatedly asked her to open the window for fresh air.

The sentence is grammatically incorrect, and the error lies in option C. The error is related to Subject Verb Agreement.

• A singular subject takes a singular verb with it in accordance with subject-verb agreement.

• Here, in the given sentence, “brother” is a singular subject and we are using “read” (a plural verb). This is wrong. We have to use the singular form of the verb - “reads”.

• For example: She plays football every day.

Thus, the correct sentence becomes:

My brother generally reads the local magazine in the morning to get the news in local language.